Sound absorbing guard rail system

ABSTRACT

A sound absorbing guard rail system for installation at a lateral or median side of a road, the guard rail system having a series of supporting posts, that are preferably vertically oriented, at least one noise absorbing panel that can be mounted to the supporting posts, and a series of longitudinal guard rails mounted on the side of the guard rail system facing the road. The noise absorbing panel comprise a noise absorbing material which is encased in an energy absorbing material provided with openings.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national stage of PCT/EP2017/067073 filedJul. 7, 2017, which claims priority of European Patent Application16178822.9 filed Jul. 11, 2016 of which is hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a sound absorbing guard rail system forinstallation at a lateral side of a road, said guard rail systemcomprises a series of supporting posts, that are preferably verticallyoriented, at least one noise absorbing panel that can be mounted to saidsupporting posts, and a series of longitudinal guard rails mounted onthe side of the guard rail system facing the road.

BACKGROUND OF THE INVENTION

A guard rail is provided at the lateral side of a road with the objectof limiting personal injuries by absorbing the energy of a vehicleveering off the road by catching and slowing down the vehicle. Added tothis primary function it is also found attractive to provide the guardrails with noise reducing means.

Accordingly, a sound absorbing guard rail of such kind is known from EP1 528 158 A1. Herein the sound absorbing panels are made of aluminium ormade transparent.

Another example of a guard rail with noise reducing measures is knownfrom WO 2010/018028 A1, where a perforated plate is provided behind theguard rail beam.

In order to ensure road safety and to reduce the risk of personalinjuries it is required that a guard rail must be able to absorb theimpact of a collision without disintegrating. This requirement is alsoapplicable to the noise reducing means. This requirement is to avoidflying objects and/or sharp fractures which can cause severe personalinjuries in case of a collision. In the guard rails with noise-reducingmeasures mentioned above, the casing in aluminium or transparentmaterials, such as glass or plastic, is brittle, costly and may notwithstand a vehicle impact without breaking apart.

By providing noise-reducing panels described above, the risk ofdisintegrating the panel during an impact is considered too high and itis therefore an object of the present invention to provide a guard railwith noise reducing means which is can withstand the impact of a vehiclecolliding with the guard rail.

SUMMARY OF THE INVENTION

According to the invention, this object is achieved by a guard rail ofthe initially mentioned kind, wherein the noise absorbing panelcomprises a noise absorbing material board which is encased in an energyabsorbing material provided with openings. Such an energy absorbingmaterial provided with openings can be formed by a mesh, a grid or aperforated material.

By the invention it is found advantageous that the noise absorbing panelis contained in an energy absorbing material, e.g. said mesh whereby animproved noise absorbing panel in a guard rail system may be achieved,which also meets the requirements concerning impact absorption andavoids disintegration at an impact with a vehicle.

The noise absorbing material is preferably a mineral wool fibre board,which has very good noise-absorbing characteristics. However, it isrealised that the noise absorbing panels can also be made with othermaterials, like foam material, integrated or partial rubber material,integrated or partial plastic material, or other noise absorbingmaterial resistant in regard to weather conditions and wear effects nextto traffic ways.

In the preferred embodiment of the invention, the energy absorbingmaterial is a stretch metal netting encasing said noise absorbingmaterial board. Stretch-metal or expanded metal provide very goodenergy-absorbing characteristics as the netting made of stretch-metalcan be deformed to a large degree when impacted. Depending on the designof the stretch metal netting it is possible to provide different stretchbehaviour in respective stress directions. E.g. it is possible toprovide a higher stress resistance and thereby a higher energyabsorption in an impact situation in longitudinal direction of thetraffic way than in vertical direction. In those directions, where thestretch metal netting provides a higher stress resistance, the meshes ofthe stretch metal netting may provide a higher amount of deformation. Inthose directions where the stretch metal netting has less stressresistance, the meshes of the stretch metal netting deform less. Thiscan be achieved e.g. by rhombus formed meshes, which have a longerdiagonal in vertical direction and a shorter diagonal in the horizontaldirection. Thereby, the ability of deformation of the rhombus formedmeshes in horizontal direction is higher than in vertical direction.Braking of the panels in any situation, in particular in acrash-situation, is to be avoided.

Moreover, in addition to the mechanical behaviour of the netting made ofstretch-metal, in particular in a stress situation, such a material canalso provide additional beneficial optical and/or mechanical effects.The stretch metal may provide a surface structure with different groupsof surfaces which are intentionally oriented into a particulardirection. Thereby, it is possible to achieve particular opticalreflection effects such that impacting light from a vehicle is reflectedin preferred directions by certain groups of surfaces of the netmaterial, whereas the impacting light is being dispersed in other lesspreferred directions. Moreover, inclining the groups of surfaces inpreferred directions may also support that particular objects collidingwith the net material may slide along the surface of the material withless friction in certain preferred directions, whereas objects impactingfrom another direction experience higher friction.

As an alternative to the stretch metal netting, the energy absorbingmaterial can be formed of perforated metal sheets, multi-slit metalsheets, plastic nets, fibre reinforced plastic or rubber material, etc.

Besides that the mineral wool fibre board, and more preferably a stonewool material, has very good noise-absorbing characteristics, anotheradvantage by in particular stone wool as the material is that thismaterial fire-resistant. The energy absorbing material, e.g. thestretch-metal netting provides protection of the mineral wool and canfurther contribute to the energy absorption at an impact due to acollision into the guard rail and the energy absorbing material, e.g.stretch-metal netting also ensures that the sound absorbing panel doesnot disintegrate at such an impact. This synergy between the mineralwool fibre board and the energy absorbing material, e.g. stretch-metalis advantageous and results in an improved noise absorbing panel in aguard rail, which also meets the requirements concerning impactabsorption and avoids disintegration at an impact with a vehicle.

By the term stretch-metal netting is meant an expanded metal sheet,which is made by a process of slit and stretch. The process may involvea precision die which slits and stretches the sheet material in a singleoperation. Expanded metal is manufactured through cutting and expandinga solid sheet of metal in special machines. The machines cut and stretchthe metal, expand it to a seamless mesh without joints. The productioncontains no welded joints and no woven threads, which contributes to theunique qualities of expanded metal. The mesh that is produced afterexpansion of the cut metal gives the material an excellent carryingcapacity.

The material is then processed through a set of rollers, which adjuststhe final thickness. The stretch-metal in the netting is a ductile metalcapable of absorbing energy while being plastically deformed.

Preferably, the stretch-metal is galvanised steel. This is advantageousas it is weather resistant and inexpensive to produce and very ductileand deformable by deforming the mesh structure of the stretch metalnetting when impacted. By galvanising the stretched metal sharp edgeswill also be rounded. However, it is by the invention realised thatother types of protective coatings, such as plastic coating, paint orthe like, may be used.

As an alternative or as a supplement to stretch-metal, the energyabsorbing mesh could be a perforated metal sheet, a plastic netting orthe like and/or a combination thereof, encasing said noise absorbingmaterial board.

In an embodiment, the netting is a panel which encloses at least themain sides and the top side of the mineral wool fibre board. Preferably,the encasing is made from the stretch-metal netting panel which is bentinto a box-like shape around the mineral wool fibre board and withmounting panels provided at each of the end sides.

By the invention it is realised that the stretch-metal netting panel maybe produced with non-stretched areas at each of the end sections forreceiving the mounting panels at each end for mounting the soundabsorber to the supporting posts. Hereby, any sharp edges or pointy endsin the netting structure may be avoided, thereby reducing any risk ofpersonal injuries to persons when handling the noise absorbing panel orduring a collision with the guard rail. Moreover, as the noise absorbingpanel may be installed in cities e.g. at parapets, this feature of theinvention prevents the risk of injuring pedestrians or cyclists.

The noise absorbing panel is preferably approx. 90 cm in height andapprox. 260 cm in length. This means that the panels may fit betweenposts in the usual guard rail structure designs. Alternatively, thepanels may be positioned behind the post, as viewed from the trafficway, wherein a pair of two consecutive posts can be arranged in adistance of approx. 1 m, 1.3 m, 2 m or 4 m, respectively. However, anydimensioning of the noise absorbing panel is encountered by the presentinvention. In particular, it is preferred to provide noise absorbingpanels in predetermined standardized dimensions which match to the usualpre-confectioned guardrail sets for different applications. By theinvention it is realised that the panels may alternatively also bemounted in front of the posts, i.e. between the posts and the guardrail. According to one embodiment of the invention, the panels are notdirectly interconnected or mechanically fixed to one another. Instead,they are mounted to the posts or the guard rail and arranged next to oneanother without a mutual fixation. In other instances, the panels can bemechanically connected.

In preferred embodiments, the mineral wool fibre board may also beprovided with a density within the range of 60-150 kg/m³, preferably80-120 kg/m³, more preferably 80-100 kg/m³. Hereby, noise absorbingpanels are provided in a size which is easy to handle during mounting.

In an embodiment, the board is preferably provided with a protectivefabric on its road-facing side. Hereby, the mineral fibre board isprotected from salt, dirt and the like from the road. The fabric may bea fleece, i.e. a non-woven fabric, which is weather and UV resistantensuring a long lifetime of the sound absorbing panel.

In addition to this feature, it is possible to provide the protectivefabric with a structured surface having different appearances dependingon the perspective. Thereby it is possible to provide optical effectsdepending on an actual line of vision. For example, the fleece andthereby the noise absorbing panel may reflect incident light more orless intensely depending on the actual incident angle. It is alsopossible to provide the protective fabric with particular lightabsorbing effects such that it has a different colour depending on theactual incident angle of light or line of vision. Thereby, the fleecemay reflect light when illuminated from one driving direction of atraffic way and fully or partially absorb or deflect light whenilluminated from the other driving direction of said traffic way.Besides design features, this feature may also provide functionalbenefits when the sound absorbing panel is installed next to trafficway.

By the present invention, it is found advantageous that the noiseabsorbing panel is provided in either a planar configuration or a curvedconfiguration. Another advantage of the stretch-metal netting encasingthe mineral fibre board is also that the stretch metal netting ismanually deformable so that the noise panel is bendable into a preferredcurved shape. As an alternative, if using more rigid less bendablepanels, shorter panels can be used and arranged in a polygonal coursefor an installation at curved traffic ways.

In an embodiment of the invention, the guard rail is made of a beam,preferably made of a steel profile in a predetermined cross-sectionalshape. The beam may be provided with sound reducing means, such as oneor more sections of perforations.

As an alternative to a profile beam, the guard rail could be a tube or awire.

According to a further embodiment of the present invention, the noiseabsorbing panel can be provided at the respective axial end portionswith end profiles. Such end profiles may have I-, H-, U- or C-shape.Using end profiles with I-, H-shape allows a connection of twoconsecutive noise absorbing panels which can be introduced in therespective recesses provided by this shape profile. U- or C-shapedprofiles can be used as end profiles of respective noise absorbingpanels in case no further noise absorbing panel is to be connected.

According to a further embodiment of the invention, end portions ofnoise absorbing panels can be at least partially covered by coverelements. Those cover elements can be formed from material which iselastically deformable and which has good noise absorbingcharacteristics, e.g from rubber material. It is possible to fix suchsingular elements to the energy absorbing mesh material on both sides ofthe noise absorbing panel, respectively. As an alternative, it ispossible to provide cover elements which cover an end portion of thenoise absorbing panel by surrounding or encompassing this end portionpartially or completely. The cover element can be fixed by additionalfixing means or it can be clamped to the noise absorbing panel. Holdingribs increasing friction or providing a form fit can be formed to thecover elements in order to engage with the noise absorbing panel, inparticular with the end portions of the energy absorbing mesh material.The cover element can provide an elastically deformable structure,preferably rounded, in the center of the end face which can be broughtin contact with the corresponding elastically deformable structure at anopposing cover element of an approximate noise absorbing panel. Theelastically deformable structure can be formed by a rounded projectionintegrally formed within the cover, e.g. with a rounded projectionsurface. This allows to compensate tolerances when mounting orassembling the system and moreover provides additional noise absorbingcharacteristics also in the interfaces between two approximate noiseabsorbing panels.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention is described in more detail withreference to the accompanying drawings, in which:

FIG. 1 is a schematic perspective view of a sound absorbing guard railsystem according to a first embodiment of the invention;

FIG. 2 is a schematic front view of said guard rail system of the firstembodiment of the invention[[,]];

FIG. 3 is a side view of the first embodiment;

FIG. 4 is a top view of the first embodiment;

FIG. 5 is a schematic perspective view of a sound absorbing guard railsystem according to a second embodiment of the invention;

FIG. 6 is a schematic front view of the second embodiment;

FIG. 7 a)-c) is a series of cross-section views illustrating theabsorption of an impact by a guard rail system according to theinvention;

FIGS. 8-10 are cross-section views of three embodiments of a noiseabsorbing panel according to the invention;

FIGS. 11-14 are cross-section views of elements of each of said threeembodiments;

FIG. 15 is a detailed front view of a preferred embodiment of astretch-metal netting according to a preferred embodiment of theinvention;

FIG. 16 is a side view of the stretch-metal netting of FIG. 15;

FIG. 17 is a schematic perspective view of an assembly profile for usebetween two adjacent noise-absorbing panels;

FIG. 18 is a front view of a guard rail beam according to an embodimentof the invention with areas of perforations;

FIG. 19 is a detailed perspective view of the beam of FIG. 18; and

FIG. 20 is a cross-sectional view of the beam of FIG. 18;

FIGS. 21 and 22 are views of a second embodiment of a guard rail beam;

FIGS. 23 and 24 are views of a third embodiment of a guard rail beam;

FIGS. 25 and 26 are two cross-sectional shapes of guard rail beams;

FIGS. 27-30 are schematic views of different perforation patterns forthe perforations in the guard rail beams of the invention; and

FIGS. 31-39 show different embodiments for designs for end elementscovering end surfaces of noise absorbing panels.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1 to 4, a first embodiment of a sound absorbingguard rail system according to the invention is shown. The guard railsystem is installed at a lateral or median side of a road 2 andcomprises a series of vertically oriented supporting posts 4. A seriesof noise absorbing panels 6 are mounted to one side of the supportingposts 4 facing away from the road and a series of longitudinal guardrails 8 are mounted on the other side of the posts 4 facing the road 2.Between the noise absorbing panels 6 assembly profiles 14 (see FIGS. 1and 2) are provided to ensure the noise absorbing panels 6 are suitablypositioned and aligned.

The noise absorbing panel 6 comprises a noise absorbing material board10 which is encased in an energy absorbing mesh 12 (see FIG. 3)

In FIGS. 5 and 6 a second embodiment of a sound absorbing guard railsystem according to the invention is shown. According to thisembodiment, the guard rails 8 are provided with perforated sections 81,82 to further increase the sound absorbing characteristics of the guardrail system.

In FIGS. 7 a) to c) the absorption of an impact by a guard rail systemaccording to the invention is shown. As vehicle comes from the road 2and collides with the guard rail 8, as indicated by the arrow in thefigures, the posts 4 deflects at ground level and the noise absorbingpanel 6 is tilted backwards, i.e. away from the road 2, as well asdeformed as the energy in the impact is absorbed in this deformation ofthe noise absorbing panel 6. As the energy is taken out of the impactthe guard rail 8 breaks away from the posts 4 as shown in FIG. 7 c).

Three embodiments of the noise absorbing panel 6 are shown in FIGS.8-10. Common for these three embodiments is that a noise absorbingmaterial board 10 is encased in an energy absorbing mesh 12. Thematerial of the noise absorbing material board 10 is preferably amineral fibre wool, and in particular stone wool material. This materialhas good sound absorbing characteristics just as the material is fireresistant and the noise absorbing panel 6 made of stone wool can therebycontribute to that the guard rail system can prevent any fire fromspreading in case a fire occurs in relation to a road accident with orwithout vehicle impact in the guard rail.

Protective profiles 16, 16′, 16″ are provided between the noiseabsorbing material board 10 and the energy absorbing mesh 12. In FIG. 11the noise absorbing material board 10 is shown alone and in FIGS. 12-14the three different designs of the protective profiles 16, 16′, 16″ areshown. The protective profile 16, 16′ or 16″ may be made of atransparent or non-transparent polymeric material, such aspolypropylene, polycarbonate or the like.

As mentioned above, the noise absorbing material board 10 is encased inan energy absorbing mesh 12. This mesh 12 is provided as a netting andis preferably made of stretch-metal or also called expanded metal. Sucha netting of expanded metal is manufactured through cutting andexpanding a solid sheet of metal in special machines. The machines cutand stretch the metal, expand it to a seamless mesh without joints. Themesh is hereby made up by ribs 12′ and rhombus-like shaped openings 12″as shown in FIGS. 15 and 16.

The mesh 12 of expanded metal is advantageous as this type of mesh ishighly deformable without breaking and can therefore absorb a highamount of energy in case of an impact and at the same time prevent thenoise absorbing material 10 encased in the mesh 12 from beingdisintegrated and scattered around the in the event of a vehicle impactof the guard rail system. The expanded metal mesh is formed such that itis more deformable in the longitudinal direction along the road than inthe vertical direction. The expanded metal mesh 12 is preferably bentinto shape so as to form cover for the front and back sides of the noiseabsorbing board 10 as well as at least the top side. Preferably, themesh 12 is also formed so it covers at least a portion of the bottomside of the noise absorbing board 10.

As mentioned in relation to FIGS. 1 and 2, an assembly profile 14 isprovided between the noise absorbing panels 6. In FIG. 17 an embodimentof the assembly profile 14 is shown. The profile 14 is made as anH-profile with two exterior flanges 142 and a web flange 144therebetween. Hereby, two receiving slots 146 are formed on each side ofthe web flange 144 for receiving the ends of two neighbouring noiseabsorbing panels 6. Alternatively two U-profiles, or Z-Profiles can beused.

In the following FIGS. 18-30 various embodiments of the guard rail beams8 are illustrated. The guard rail beams 8 are formed from a sheet ofmetal which is bent into a desired cross-sectional shape. In theembodiment shown in FIGS. 18-20, the guard rail beam 8 is shaped withupper and lower longitudinal flange portions facing the road and acentral flange portion therebetween. The upper and lower flange portionsare provided with perforated sections 81 and the central flange portionis also provided with a perforated section 82. Mounting holes 80 areprovided at least at the end portions of the beams 8.

In FIGS. 21 and 22 another embodiment is shown of the beam design. Thissecond design differs from the design shown in FIGS. 18-20 by havingnon-perforated sections 83 along the beam 8.

In FIGS. 23-24, yet another variant of the design of the perforations isshown, where only areas 84 around the mounting holes 80 arenon-perforated.

FIGS. 25 and 26 show cross-sections of two alternative shapes of theguard rail beam 8 relative to the shape shown in FIG. 20, which could beused for the road-facing guard rail beams 8 in a guard rail systemaccording to the invention.

The perforations may be provided in the guard rail beams 8 withdifferent patterns. In FIGS. 27-30 some different perforation patternsare shown.

FIG. 31 shows a detailed view of an end region of a noise absorbingpanels 6 as described above. At the end region of the noise absorbingpanel 6, two rubber elements 200 are fixed to the edges of the energyabsorbing mesh material 12. Each of the rubber elements 200 incross-section provides a profile with a U-shaped receiving part 202 withrib-like projections 204 and 206. Moreover, each of the rubber elements200 has a hollow oval ring part 208. The rubber elements 200 are fixedto the free edge of the mesh material 12 by means of the receiving parts202, wherein the rib-like projections 204 and 206 engage the meshmaterial 12 in order to retain the rubber elements 200 on the free edgeof the mesh material 12. The hollow oval ring parts 208, which can beelastically deformed, project from the front surface 210 of the noiseabsorbing panel 6. Thereby, the rubber elements 200 provide a noisedamping and mechanically cushioning interface to an approximate wallelement or to another noise absorbing panel 6 formed with correspondingrubber elements 200. Moreover, tolerances can be compensated thereby.

It is to be added that the noise absorbing panel 6 also shows anadditional protection layer 212 formed between the noise absorbingmaterial board 10 and the energy absorbing mesh material 12. Thisadditional protection layer 212 can be provided for protecting the noiseabsorbing material board 10 from dirt, water, or other externalinfluences. Moreover, it can provide optical effects, e.g. particularreflection effects or light absorbing effects depending certain angularranges. This additional protection layer can be provided in eachembodiment as described above, independent from other structuralfeatures described.

FIG. 32 shows an alternative embodiment for the design of an end coverdesign of a noise absorbing panel 6. The noise absorbing panel 6 at itsfree and is provided with a cover 220 formed from rubber material. Thecover has bent edge regions 222 which encompass the free ends of thenoise absorbing panel 6 and are held by elastic deformation and frictionto the end regions of the energy absorbing mesh material 12.

FIG. 33 shows an embodiment for another cover 230 according to theinvention which basically corresponds to the embodiment as described inregard to FIG. 32. FIG. 35 additionally shows how two opposing noiseabsorbing panels 6 and 6′ are arranged against one another equipped withcovers 230, respectively. Moreover, FIG. 36 additionally shows aperspective view of the cover 230. According to this embodiment, thecover 230 has basically the same shape as shown in FIG. 32 in regard thecover 220 and it is also formed from elastically deformable material,e.g. rubber. Additionally, the cover 230 provides in its central regiona rounded projection 232 with a hollow interior 234, which makes therounded projection 232 elastically deformable. The general shape of thecover 230 is adapted to the geometry of the end side of a noiseabsorbing panel 6, as can be seen in FIG. 36. When fixed onto the end oftwo opposing noise absorbing panels 6 and 6′, as shown in FIG. 35, thetwo corresponding rounded projections 232 and 232′ of the respectivecovers 230 and 230′ contact one another and under elastic deformationprovide a tight engagement of the two end covers 230 and 230′. Thisallows to compensate tolerances and provides a tight connection andadditional noise damping effects also in the interface between twoapproximate noise absorbing panels 6 and 6′.

FIG. 34 shows another embodiment which is based on the embodimentaccording to FIG. 33. The end cover 240 corresponds in its shape to theend cover 230 as described above, i.e. it also has a rounded projection242 with a hollow interior 244. In the interior of the projection 242 apartition wall 246 is provided extending from the inner surface of theprojection 242 into the noise absorbing material board 10. The partitionwall 246 additionally stabilizes the structure of the projection 242.

FIG. 37 shows a further embodiment which is also based on the embodimentaccording to FIG. 33. In this embodiment, in the central area of thecover 250 the projection is formed by a closed ring-like structure 252as can be seen in the cross-section with a hollow interior 254. Thecover 250 is plugged onto the end portion of the noise absorbing panel 6such that a part, in the example about one fourth of the circumference,of the inner portion 256 of the closed ring-like structure 252 engagesthe front surface of the noise absorbing material board 10 and protrudesinto it to a certain degree. This further stabilizes the cover 250 andallows to compensate tolerances. As can be seen in FIG. 39, the shape ofthe cover 250 is similar to the shape as already described in regard toFIG. 36.

Finally, as can be seen in FIG. 38, this embodiment provides a similarinterface between two opposing or approximate noise absorbing panels 6and 6′ wherein the two ring-like structures 252 contact each other undera demanded elastic deformation in order to provide a tight fit withbeneficial noise dampening and cushioning characteristics.

Above, the invention is described with reference to some currentlypreferred embodiments. However, it is realised that other embodimentsmay be provided without departing from the scope of the invention asdefined in the accompanying claims.

1-20. (canceled)
 21. A guard rail system for installation at a lateralor median side of a road, the guard rail system comprising: a series ofsupporting posts; at least one noise absorbing panel mounted to thesupporting posts, the noise absorbing panel comprising a noise absorbingmaterial encased in an energy absorbing material provided with openings;and a series of longitudinal guard rails mounted on a side of the guardrail system facing a road.
 22. A guard rail system according to claim21, wherein the noise absorbing material is a mineral wool fibrematerial provided as a board, foam material, integrated or partialrubber material, integrated or partial plastic material, or other noiseabsorbing material resistant in regard to weather conditions and weareffects next to traffic ways.
 23. A guard rail system according to claim21, wherein the energy absorbing material provided with openingscomprises a mesh, a grid or a perforated material.
 24. A guard railsystem according to claim 21, wherein the energy absorbing material is astretch-metal netting encasing the noise absorbing material.
 25. A guardrail system according to claim 24, wherein the stretch-metal is aductile metal capable of absorbing energy while being plasticallydeformed.
 26. A guard rail system according to claim 24, wherein thestretch-metal is galvanised steel.
 27. A guard rail system according toclaim 21, wherein the energy absorbing material is a perforated metalsheet, a plastic netting and/or a combination thereof, encasing thenoise absorbing material.
 28. A guard rail system according to claim 24,wherein the noise absorbing material has main sides and a top side, andthe netting is a panel which encloses at least the main sides and thetop side of the noise absorbing material.
 29. A guard rail systemaccording to claim 24, wherein the encasing is made from a stretch-metalnetting panel which is bent into the box-like shape around the noiseabsorbing material and with mounting panels provided at each of the endsides of the stretch-metal netting panel.
 30. A guard rail systemaccording to claim 24, wherein the encasing is made from a stretch-metalnetting panel which is cast into an insulation material made by awet-felt process and with mounting panels provided at each of the endsides of the stretch-metal netting panel.
 31. A guard rail systemaccording to claim 24, wherein the encasing is made from a stretch-metalnetting panel and mounting panels are provided at each of the end sidesof the stretch-metal netting panel, the stretch-metal netting panelbeing produced with non-stretched areas at each of the end sections forreceiving the mounting panels at each end for mounting the noiseabsorbing panel to the supporting posts.
 32. A guard rail systemaccording to claim 21, wherein the noise absorbing panel is approx. 90cm in height and in length approx. 130 cm, approx. 260 cm, approx. 520cm, or approx. 530 cm.
 33. A guard rail system according to claim 22,wherein the noise absorbing material is a mineral wool fibre boardcomprising stone wool and is provided with a density within the range of60-150 kg/m³, 80-120 kg/m³, or 80-100 kg/m³.
 34. A guard rail systemaccording to claim 21, wherein the noise absorbing material is providedwith a protective fabric on its road-facing side.
 35. A guard railsystem according to claim 34, wherein the protective fabric has astructured surface having different appearances depending on an actualline of vision.
 36. A guard rail system according to claim 21, whereinthe noise absorbing panel is provided in a planar configuration or acurved or polygonal configuration.
 37. A guard rail system according toclaim 21, wherein the noise absorbing panel is provided at therespective axial end portions with end profiles, and the end profileshave a I-, H-, U- or C-shape.
 38. A guard rail system according to claim21, wherein the guard rail is made of a steel beam having apredetermined cross-sectional shape.
 39. A guard rail system accordingto claim 38, wherein the beam is provided with sound reducing means,comprising one or more sections of perforations.
 40. A guard rail systemaccording to claim 21, wherein the guard rail is a tube or a wire.